ABSTRACT:The objective of the present study was to formulate and develop extended release drug delivery system of anti-epileptic drug Sodium valproate (VAS) and Valproic acid (VA) in the ratio of 70:30 with extended release profile. Preliminary studies with different polymers such as HPMC K15M, PVP K90, Ethyl cellulose N50, Carbopol were performed. The results of in-vitro release data showed that HPMC K15M can sustain the drug release upto 24hr. From these studies HPMC K15M has been selected for further studies. HPMCK15M was used along with HEC 250HX to retard the drug release. VAS and VA extended release tablets were prepared by wet granulation method. The hardness of these extended release tablets was within the range between 5.63±0.42 to 6.92±0.33 kg/cm2. The drug content was within the range, 97.23±0.25 to 102.03±2.45%. The in-vitro VAS and VA release from the tablets was found sustained over 24 hours with Higuchi kinetics of drug release and release pattern followed anomalous (Non-Fickian) diffusion. The Fourier transform Infrared spectroscopy analyses indicated that there was absence of chemical interaction between the drug and the excipients. The dissolution profiles of the developed formulation and the commercial tablet formulation, Encorate, were compared using the similarity factor (f2) and difference factor (f1). The released profile of tablet containing 15% HPMC K15M and 15% HEC 250HX by weight was similar to that of Encorate® providing the values of similarity factor (f2) and difference factor (f1) of 88.20 and 3.22 respectively.